Can I transfer files using Kafka?

Question

I have thousands of files created every day that I want to transfer using Kafka. When I try to read a file, each line is taken as a separate message.

I would like to know how I can make each content of a file as one message in a Kafka topic and with the consumer how to write each message from a Kafka topic in a separate file.

Answer 1

You can write your own serializer / deserializer for processing files. For instance:

Producer Support:

props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, org.apache.kafka.common.serialization.StringSerializer);  
props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, YOUR_FILE_SERIALIZER_URI);

Consumer details:

props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, org.apache.kafka.common.serialization.StringDeserializer);
props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, YOUR_FILE_DESERIALIZER_URI);

Serializer

public class FileMapSerializer implements Serializer<Map<?,?>> {

@Override
public void close() {

}

@Override
public void configure(Map configs, boolean isKey) {
}

@Override
public byte[] serialize(String topic, Map data) {
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    ObjectOutput out = null;
    byte[] bytes = null;
    try {
        out = new ObjectOutputStream(bos);
        out.writeObject(data);
        bytes = bos.toByteArray();
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        try {
            if (out != null) {
                out.close();
            }
        } catch (IOException ex) {
            // ignore close exception
        }
        try {
            bos.close();
        } catch (IOException ex) {
            // ignore close exception
        }
    }
    return bytes;
}
}

deserializer

public class MapDeserializer implements Deserializer<Map> {

@Override
public void close() {

}

@Override
public void configure(Map config, boolean isKey) {

}

@Override
public Map deserialize(String topic, byte[] message) {
    ByteArrayInputStream bis = new ByteArrayInputStream(message);
    ObjectInput in = null;
    try {
        in = new ObjectInputStream(bis);
        Object o = in.readObject();
        if (o instanceof Map) {
            return (Map) o;
        } else
            return new HashMap<String, String>();
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        try {
            bis.close();
        } catch (IOException ex) {
        }
        try {
            if (in != null) {
                in.close();
            }
        } catch (IOException ex) {
            // ignore close exception
        }
    }
    return new HashMap<String, String>();
}
}

Compose messages in the following form

final Object kafkaMessage = new ProducerRecord<String, Map>((String) <TOPIC>,Integer.toString(messageId++), messageMap);

messageMap fileName . . , File_Name FileContent. .